# 6. Look up a hash on the central Verae chain

Zapier search: **Find Timestamp by SHA256**.

Middleware: `GET /zapier/v1/hashes/{sha256}`.

This asks the **main Verae chain** (or its mock) whether that digest was **itemized** as its own seal.

| Result | Meaning |
|--------|---------|
| One record, `exists: true`, `itemizedOnMainChain: true` | This hash has its own certificate. Use `jobId` / `receipts[0]`. |
| Empty / `exists: false` | Not itemized on the main chain. It may still exist as a **leaf** of a bulk summary — use [tree-node lookup](09-lookup-tree-nodes.md). |

Searches in Zapier must return a list. Zero hits is a miss (the Zap can follow the “not found” path). Errors other than 404 fail the step.

## When central lookup is the right tool

- You registered with **Create Timestamp** (single item).
- You stored the `sha256` from that Zap and want to confirm the seal later.
- You are verifying someone else’s **itemized** hash (they gave you 64 hex chars that they sealed individually).

## When it is the wrong tool

- The hash was submitted in **Create Batch Timestamps**. The chain stored the Merkle **root**, not this leaf. Central lookup will miss. Continue to tree nodes.